Digital Design And Modeling Analysis Of Fan Coil

With the increasingly wide use of fan coil unit system in domestic buildings, theoretical research of heat and mass transfer as well as structural design and simulation has become a hot point in the field of refrigeration and air-conditioning. Against this background, research of the design and simulation of fan coil is carried out in this paper, mainly in the following several aspects.Calculation of the physical properties of moist air is studied and two applicable and efficient fitted formulas are presented to calculate the temperature of saturated steam in light of its pressure. These two formulas are more accurate than the one presented in the ASHRAE Handbook. Also, iteration model of the physical properties of moist air is established. On the basis of all this work, the calculation program model of the physical properties of moist air is established, which is an important technological base for the design and simulation of fan coil.The mathematical models of fan coil under various operating conditions are established and the parameters involved are analyzed. On the basis, appropriate and effective algorithms are devised to solve the models in order to design the structural parameters of fan coil under the following three conditions respectively, given air volume flow rate and outlet water temperature, given outlet air dry bulb and wet bulb temperature, and given outlet air relative humidity and outlet water temperature. Three design models are presented so as to meet the different requirements of different circumstances. After that, fan coil is simulated under cooling and heating conditions respectively and the algorithms are studied in details. The algorithms of both the design and simulation are optimized so that the problems of deciding the operating conditions as well as handling the extreme conditions are properly solved, improving the stability, convergence and calculation speed.The simulation models of fan coil are validated by experimental data and the results show that the simulation and experimental data match well both in numerical value and changing trend. All these prove that the mathematical models and their corresponding algorithms are relatively accurate and effective.On the basis of numerous calculations, the performance of fan coil under varying operating conditions and structures are studied. This gave a base to understand the changing trend of its performance and to optimize the running parameters and structural parameters.The professional and object-oriented design and simulation software for fan coil is developed using Visual Basic, based on the previous design and simulation model. The calculation of software, which boasts high applicable values for the designers and consumers of fan coil, is relatively accurate, speedy and has a friendly operating interface.